Grading apparatus



Nov. 7, 1944. D. s. GLENN GRADING APPARATUS Filed April 28, 1941 INVENTOR. DA WEENCE 5. 0L N/V Patented Nov. 7, 1944 UNITED STATES PATENT OFFICE GRADING APPARATUS Dawrence S. GlenmDavis, Calif. Application April 28, 1941, Serial No. 390,647

7 Claims.

My invention relates to grading apparatus, and more particularly, to apparatus for the grading of items which diiTer but slightly in specific gravity, such as fruits, vegetables, and the like.

In the grading of fruits or vegetables, etc., advantage is taken of the fact that the ripe and more tender items are usually of slightly lower specific gravity than those which are less ripe and less tender. Apparatus of the prior art, with which I am familiar, designed for the purpose of grading fruits-or vegetables, customarily make use of a brine solution of a specific gravity somewhere in between the maximum and minimum specific gravities of the items to be graded. When such items are dumped into such solution, those of a lower specific gravity rise to the surface, while the others sink to the bottom, and, in this manner, grading of the items is realized.

This method is relatively uneconomical in requiring substantial quantities of salt with which to prepare and replenish the brine solution, the use of which necessitates a subsequent washing operation to rid the graded items of such salt and other foreign matter. The method is relatively ineiiicient in being limited in its results to the separation of the items into two grades only, and furthermore, requires close and continuous supervision to maintain the specific gravity of the brine within narrow limits. In addition, the grading by this method is relatively slow, and the corrosive action of a salt atmosphere upon exposed metal in the neighborhood of the apparatus must be a factor to be contended with.

Among theobl'ects of my invention are- (1) To provide a novel and improved apparatus, capable of increased speed of grading;

(2) To provide a novel and improved apparatus, adapted during the process of grading, to separate foreign matter, such as trash, sticks, buds, sand, etc., from theitemsto be graded;

(3) To provide a novel and improved apparatus, which is not limited to the separation of items into two grades only, but which is especially well adapted for multiple grading;

(4) To provide a novel and improved apparatus, the operation of which is based upon a simplified process of grading;

(5) To provide a novel and improved apparatus,s'usceptible to fine and delicate preliminary adjustments, to adapt the same for a desired ut of a product, or for the grading of "fierent range of sizes and specific d lii, tus, hich require wider.

after the apparatus has been once adjusted for ratus, which may be expanded to automatically distribute the graded product to stations for subsequent handling;

(9) To provide a novel and improved apparatus, which may readily and conveniently be cleaned within a very brief shut-down period;

(10) To provide a novel and improved method of grading items which diifer but slightly in specific gravity. a

Additional objects of my invention will be brought out in the following description of the same taken inconjunction with the accompanying drawing wherein- Figure 1 is a side elevational view in section through one embodiment of my invention;

Figure 2 is a plan view looking down on the apparatus of Figure 1;

Figure 3 is a front elevational view of the same apparatus;

Figure 4 is a schematic showing of the apparatus of the preceding figures expanded to provide for automatic distribution of the graded product to stations for subsequent handling.

Referring to the drawing for a detailed description of my invention, the apparatus involves a grading channel I having an input end 9 and a discharge end I I, the channel being formed by a pair of parallel side walls l3 closely spaced, and joined by a floor l5 alOng the bottom edges thereof. This construction provides for a channel which is quite narrow in comparison to its length and depth, the approximate width being determined largely by the size of the items to be handled by the apparatus.

The grading channel receives a supply of liquid from a supply reservoir ll of approximately the same depth as the channel, but considerably The supplyreservoir is joined to the channel by a gradual tapering of the reservoir, this taper serving to smooth out any turbulence in the liquid flowing from the supply reservoir into the grading channel, whereby the flow of liquid through the grading channel will be uniform and free of eddies and the like.

An important feature of the design of my grading channel resides in the fact that it is maintained open "at the discharge end ll thereof, eitherby providing a perforated wall at that end out the grading channel, may

of the channel, but preferably by leaving the end open all the way from the floor up.

In the operation of the channel, in accordance with the method of grading proposed by me, it is essential to maintain a substantial depth of liquid throughout the channel, including the discharge end thereof, or in other words, it is necessary to maintain a relatively high liquid level IS in the channel. This condition can be realized with an open end grading channel, by feeding liquid to the supply reservoir H at a rate which will raise the. level to the required height and maintain the same by compensating for the discharge through the open end of the channel. The discharge, under these conditions, will exist and be maintained at various elevations above the floor of the channel.

The liquid required for the building up and maintaining of the high liquid level I9 throughbe supplied to the supply reservoir l1 from a discharge reservoir 2| by means of a pump 23 connected into a pipe line 25 extending from the discharge reservoir 2| to the supply reservoir l1. The discharge reservoir is so designated, because it is preferably located beneath the discharge end ll of the grading channel to retrieve the discharged liquid for recirculation in the apparatus. Of course, where 'an inexhaustible and cheap supply of liquid is available, the discharge reservoir may be eliminated from the system, and liquid discharged from the channel be discarded.

Rather than leave the discharge end H of the grading channel open to the full width of the channel, material advantages may be attained by restricting the discharge end somewhat, although not to the extent of impeding the passage therethrough of the items to be graded. Such restriction will facilitate maintenance of the proper liquid level, and, in addition, will materially cut down the rate of discharge of the liquid. This will enable a corresponding reduction in the load on the pump 23, whereby the economy of operation will be considerably enhanced.

Such restriction of the discharge end of the channel may be realized by gradually tapering the channel toward its discharge end, but I prefer to retain the channel walls l3 parallel, and obtain the desired restriction of the discharge end by providing a gate 21 formed by a pair of gate elements 29, each hingedly secured to a channel wall l3 at its discharge end, and both elements cooperating to enable adjustment of the discharge opening to thereby obtain any -degree of restriction desired. A suitable locking screw 3|, or other locking means, may be embodied in the gate structure to hold the gate in any adjusted position against the force of the discharge through the open end of the channel. Such locking screw 3|, when employed, passesthrough a slotted bracket 32, to which the associated gate element is clamped after adjustment thereof.

At various elevations, at the discharge end of the grading channel, I dispose what may conveniently be termed grading screens 33, each of which is inclined downwardly to a suitable receptacle 35.

The material 3! to be graded is deposited into a hopper 39 supported above the receiving end 9 of the grading channel, its discharge end terminating at or slightly below the liquid level l9. Immediately below the discharge end of the hopper, I provide a platform 4|, which may be supported by the side walls |3 of the grading channel. This platform is preferably free of end walls, so that the flow of liquid across the surface of the platform may take place uninterrupted.

In the operation of my improved grading apparatus, the items settling upon the platform 4| from the hopper, are carried off by the flow of the liquid over such platform, and immediately begin to settle or rise at a rate depending upon the relative specific gravity of each individual item, to that of the liquid. Those items which may be of lighter specific gravity than the liquid will rise to the surface, and of those of greater specific gravity, the denser items will settle at a more rapid rate than the others. At the discharge end of the channel the relative elevational positions of the various items in the discharge, will be in accordance with their relative specific gravities, and these items will be carried off by the discharge and deposited upon the various grading screens, from which they will roll into the receptacles 35, the liquid dropping through the screen to the discharge reservoir below. The platform 4| is essential in obtaining maximum efliciency in the operation of my improved apparatus, in that, because of its presence, all of the items will start off under practically identical conditions, whereby their relative elevational positions at the discharge end of the channel will be a true and accurate measure of their respective specific gravities.

My improved apparatus lends itself to simple but yet very fine adjustments in obtaining any desired character of grading. In as much as the elevational positions of the various items at the discharge end of the grading channel is primarily a matter of timing, it will be apparent that by timing the arrival of these items, variations in the character of the grading may be realized. Such timing may be controlled in many ways in the apparatus described by me. One way is to increase the rate of flow of liquid through the grading channel by varying the adjustment of the gate 21, at the same time altering the output of the pump 23 accordingly, to maintain the proper liquid level l9. Another way in which such timing may be varied is to shift the position or the hopper 39 and platform 4| with respect to the discharge end II of the grading channel. A combination of both methods of timing may also be relied upon, if desired.

While my apparatus may be operated upon the basis of conventional apparatus of the prior art, that is, by utilizing a brine solution of a specific gravity lying somewhere in between the maximum and minimum specific gravities of the items to be graded, it is not necessarily limited to the use of such method. In fact, I consider, as a very important phase of my invention, the fact that my improved apparatus lends itself to the use of ordinary water as a circulating fluid, and this, in itself, imparts considerable advantages to my invention over such apparatus of the prior art which requires the use of a brine solution. It will be found, with most fruits or vegetables that are customarily graded in apparatus employing brine solutions, that such fruits or vegetables have a range of specific gravities greater than that of water, and therefore such items will sink when placed in water. When employing my improved apparatus for the grading of such items, I can adjust the timing to such a fine degree, that a maximum spread of the items may be obtained at the discharge end between a point slightly above the bottom l5 and a point slightly below the level IQ of the liquid. Such adjustment has the advantage, that in the operation of the ap- 'paratus, any foreign matter, such as sticks or.

flower buds, or the like, will readily float upon the surface of the liquid, and such foreign matter, as sand or gravel, will promptly settle to that employs a brine solution.

'It will be apparent also, from the verynature of my improved grading apparatus, that the .number of grades and the character of the various grades, is purely a matter of the number and positioning of the grading screens 33 at the discharge end of the grading channel, and these may be varied both in number and position to suit conditions. Additional variation in the character of the graded product may also be obtained by altering the time of arrival of such items at the discharge end of the channel.

Where the apparatus is designed to handle items of substantial size, it may be of advantage to alter the gate structure at the discharge end of the channel to maintain a uniform velocity of discharge at the various elevations. This may be advantageously realized by tapering the gate ele- I be independently shifted to any desired position and then clamped by means of the thumb screws to hold them in such adjusted positions.

pipes, or through the use of baflles, or a combinationof any or all of the above devices.

It will be apparent that my improved apparatus is based upon a simplified and novel method of grading, and in its operation fulfills all the objects of my invention, as previously set forth. Because of its simplicity of construction and the fact that it lends itself to the use of water in lieu of brine, the apparatus is very economical both in the matter of construction and in operation. The use of water, further, eliminates the necessity for maintaining close supervision over spe- My improved apparatus lends itself very con- I uctto such stations in the discharge liquid, at

which stations the conveyors each may include a screen 5| to permit of the separation of the liquid, leaving the product available for whatever operation has to be performed in connection therewith. The liquid so discharged may be conveyed back to the discharge reservoir 2| or may be discarded.

The chutes 49 may be formed of pipe sections,

and when so constructed, the diameter may be such as to create a back pressure without obstructing the free passage of the graded product. Such back pressure offers the advantage of facilitating the maintenance of a high liquid level in the open ended grading channel, at the same time further slowing up the velocity of flow and thereby enhancing the economy of operation of the apparatus. It is understood, of course, that for any given material to be graded and to obtain a desired graded output, the location of the hopper and platform will vary with the velocity of flow of the material through the grading channel.

A similar back pressure may also be realized by cific gravity of the liquid, as is the case with the method employing a brine solution.

The design of the apparatus is such as to be very conservative in floor space, and in as much as it requires practically no supervision during operation, the same may be installed against a wall in some out of the way section of a room, where floor space is not at a premium.

No difliculty is experienced in the cleaning of the apparatus, for during operation it is being continually exposed to the washing effect of the running water. The discharge reservoir will inherently function as a settling tank for foreign matter of high specific gravity such as sand, gravel, etc., and should an accumulation of such material occur in the grading channel, the same can be flushed out with a hose, within a, few moments during normal shut-down periods.

Above all, my invention very convehiently'and accurately permits of the grading of a product into as many grades as desired with the highest assurance of realizing uniformity in the graded output.

While I have described one embodiment of my invention in detail, it is susceptible to change and modification, without departing from the principles involved, and I therefore do not desire to be limited in my protection to the specific details described and illustrated, except as may be necessitated by the appended claims.

I claim:

1. Grading apparatus comprising, a grading channel having a substantially uniform geometrical cross section, a continuous planar floor surface and an open end; means for maintaining a flow of liquid of substantially uniform depth and uniform cross-sectional velocity in said. channel, said flow terminating in a discharge of liquid from said open end at'various elevations above the floor of said channel, a pump adapted to convey liquid from-a source of supply to said grading channel, and a reservoir in the flow path of said liquid from said pump tosaid grading channel and having an end opening communicating with said channel for substantially the entire height thereof, said reservoir having a cross section normal to said flow, substantially greater than the corresponding cross section of said grading channel, whereby said reservoir will absorb fluctuations in the input of said pump to preclude such fluctuations from being carried over into said grading channel; means for placing items to be graded into said grading channel adjacent the upper level of the flowing liquid therein; and means at the open end of said channel for segregating such items in accordance with their elevational position upon reaching the open end of said channel.

2. Grading apparatus comprising a grading channel of narrow width and substantial depth and having an end thereof open for discharge, a pump adapted to convey liquid from a source of incorporating a reverse curve in the chutes or 7 s p y t said ad a a d a reservoir in the flow path of said liquid from said pump to said grading channel and having a lateral opening communicating with said channel forsubstantially the entire height thereof, said reservoir having a cross section normal to said flow, substantially greater than the corresponding cross section of said grading channel whereby said reservoir will absorb fluctuations in the input of said pump to preclude such fluctuations from being carried over into said grading channel.

3. Grading apparatus comprising a grading channel having an end thereof open for discharge; and means for supplying liquid to said channel during operation of said apparatus including a source of liquid, a pump associated with said source, and a reservoir intermediate the output of said pum and said grading channel and having a lateral opening in communication with said channel for substantially the entire height thereof, said reservoir having substantially greater capacity than said channel, whereby fluctuations in said pump output-will not be reflected in detrimental variations in the liquid level of said grading channel.

4. Grading apparatus comprising a grading channel having an end thereof open for discharge; and means for supplying liquid to said channel during operation of said apparatus including a source of liquid, a pump associated with said source, and a reservoir intermediate the output of said pump and said grading channel, said reservoir being in open lateral communication with said channel for substantially the entire height thereof and having substantially greater capacity than said channel. whereby fluctuations in said pump output will not be reflected in detrimental variations in the liquid level of said grading channel.

- 5. Grading apparatus comprising, a grading channel having a continuous planar floor surface, an input end and a discharge end, said discharge end being open at various elevations above the floor of said channel; a gate including a pair of plates, each plate thereof pivotally mounted about a vertical axis on opposite sides of the open end of said channel; means cooperating with said plates for maintaining the same in adjusted positions; means for supplying a suflicient flow of liquid to said grading channel to maintain a means at the open end of said channel for segregating such' items in accordance with their elevational position in said liquid upon reaching the open end of said channel.

6. Grading apparatus comprising, a grading channel having a continuous planar floor surface, an input end and a discharge end, said discharge end being open at various elevations above the floor ofsaid channel; means including a reservoir for supplying a sufiicient flow of liquid to the input end of said grading channel to maintain a liquid level in said grading channel above said various elevations, means for, supplying liquid to said reservoir in amounts suflicient to compensate for that flowing out of the reservoir into the grading channel, said reservoir being of considerably greater width than said grading channel and having a tapering connection to the input end of said channel to eliminate turbulence in the flow of such liquid through said channel and stabilize the depth of said flow of liquid through said channel means for placing into said grading channel, items to be graded; and means at the open end of said channel for segregating such items in. accordance with their elevational position upon reaching the open end of said channel.

7. Grading apparatus comprising, a grading channel including a pair of parallel smooth side walls and a level bottom having a continuous planar floor surface and terminating in an open discharge end; means including a reservoir in open and unobstructed communication with said channel throughout substantially the height of said channel and an adjustable gate at the open end thereof to cooperate with said reservoir in maintaining a uniform flow of liquid of substantial depth, through said channel and said open end; means for placing items to be graded, in said channel at a distance from the open end thereof, said means including a thin horizontally disposed platform supported slightly below the liquid level in said channel, and a hopper having a discharge opening in proximity to said platform; means including a plurality of screens at various elevations adjacent the open end of said channel for segregating such items in accordance with their elevational position upon their arrival at the open end of said channel; and means for adjusting said apparatus to obtain a desired elevational distribution of such items at said open end of the grading channel.

DAWRENCE S. GLENN. 

